单选题Housewives who do not go out to work often feel they are not working to their full ability.

单选题Her life is becoming more diverse .

单选题Most people would agree that, although our age far {{U}}surpasses{{/U}} all previous ages in knowledge, there has been no correlative increase in wisdom. A. improves B. precedes C. imposes D. exceeds

单选题Human Heart Can Make New Cells Solving a longstanding mystery, scientists have found that the human heart continues to generate new cardiac cells throughout the life span, although the rate of new cell production slows with age. The finding, published in the April 3 issue of Science, could open a new path for the treatment of heart diseases such as heart failure and heart attack, experts say. "We find that the beating cells in the heart, cardiomyocytes, are renewed," said lead researcher Dr. Jonas Frisen, a professor of stem cell research at the Karolinska Institute in Stockholm, Sweden. "It has previously not been known whether we were limited to the cardiomyocytes we are born with or if they could be renewed," he said. The process of renewing these ceils changes over time, Frisen added. In a 20-year-old, about 1 percent of cardiomyocytes are exchanged each year, but the turnover rate decreases with age to only 0.45 percent by age 75. "If we can understand how the generation of new cardiomyocytes is regulated, it may potentially possible to develop pharmaceuticals that promote this process to stimulate regeneration after, for example, a heart attack," Frisen said. That could lead to treatment that helps restore damaged hearts. "A lot of people suffer from chronic heart failure," noted co-author Dr. Ratan Bhardwaj, also from the Karolinska Institute. "Chronic heart failure arises from heart cells dying," he said. With this finding, scientists are "opening the door to potential therapies to having ourselves heal ourselves," Bhardwaj said. "Maybe one could devise a pharmaceutical agent that would make heart cells make new and more cells to overcome the problem they are facing." But barriers remain. According to Bhardwaj, scientists do not yet know how to increase heart cell production to a rate that would replace cells faster than they are dying off, especially in older patients with heart failure. In addition, the number of new cells the heart produces was estimated using healthy hearts--whether the rate of cell turnover in diseased hearts is the same remains unknown.

单选题Multivitamins Urged for All Pregnant Women A recent study in Tanzania found that when pregnant women took vitamins every day, fewer babies were born too small. Babies that weigh less than two and one-half kilograms at birth have a greater risk of dying. Those that survive are more likely to experience problems with their development. And experts say that as adults they have a higher risk of diseases including heart disease. The World Health Organization estimates that every year twenty million babies are born with low birth weight. Nine out of ten of them are born in developing countries. The new study took place in Dubai. 4,200 pregnant women received multivitamins. The pills contained all of the vitamins in the B group along with vitamins C and E. They also contained several times more iron than the levels advised for women in developed nations. Pregnant women especially in poor countries may find it difficult to get enough vitamins and minerals from the foods in their diet. The scientists compared the findings with results from a group of 4,000 women who did not receive the vitamins. A report by the scientists, from the United States and Tanzania, appeared in the New England Journal of Medicine . Wafaie Fawzi of the Harvard University School of Public Health led the study. None of the women in the study had HIV, the virus that causes AIDS. The scientists reported earlier that daily multivitamins were a low-cost way to reduce fetal deaths in pregnant women infected with HIV. The earlier work in Tanzania also found improvement in the mothers in their number of blood cells known as lymphocytes (淋巴细胞). Lymphocytes increase the body"s immunity against infection. The new study in pregnant women who were not infected with the AIDS virus found that multivitamins reduced the risk of low birth weight. Just under eight percent of the babies born to women who took the multivitamins weighed less than 2,500 grams. The rate was almost nine and one-half percent in the group of women who received a placebo, an inactive pill, instead of the vitamins. But the vitamins did not do much to reduce the rates of babies being born too early or dying while still a fetus. Still, the researchers say multivitamins should be considered for all pregnant women in developing countries.

单选题You don't need to carry large amounts of cash; actually all financial business will be conducted by computers. A. transmissions B. transitions C. transactions D. transportation

单选题William Wrigley first started to experiment with chewing gum.

单选题They had a far better {{U}}yield{{/U}} than any other farm miles away around this year. A. goods B. soil C. climate D. harvest

单选题This sort of thing is bound to happen.

单选题 Effects of Exercise on Elderly Diabetics (糖尿病人) Most older people with. so-called type 2 diabetes (糖尿病) could stop taking insulin (胰岛素) if they would do brisk (轻快的) exercise for 30 minutes just three times a week, according to new medical research results reported in a Copenhagen newspaper. Results from tests conducted on diabetics at the Copenhagen central hospital Rigshospitalet's Center for Muscle Research showed that physical exercise can boost the body's ability to make use of insulin by 30 per cent. This is equal to the effect most elderly diabetics get from their insulin medication (药物治疗) today. Researchers had a group of non-diabetic men and a group of men with type 2 diabetes, all more than 60 years of age, exercise on bicycles six times a week for three months. After the three months the doctors measured how much sugar the test subjects' muscles could make use of as a measure for how well their insulin worked. Associate Professor Dr Flemming Dela of the Muscle Research Center said the tests demonstrated that the exercising diabetics had made as good use of insulin as the healthy non-diabetic persons. "This means that the insulin works just as well for both groups. Physical exercise cannot cure people of diabetes, but it can eliminate almost all their symptoms. At the same time it can put off the point at which they have to begin taking insulin," Dela said. Insulin is a hormone produced by the pancreas (胰腺), controlling sugar in the body and is used against diabetes. Dela said that to achieve the desired effect diabetics need only exercise to the point where they begin to sweat, but that the activity has to be maintained since it wears off after five days without sufficient exercise. Most diabetics realize that they have to watch their diet while remaining unaware of the importance of exercise, Dela added.

单选题The book provides a concise analysis of the country"s history.

单选题Did she accept his research proposalA. invitationB. planC. offerD. view

单选题Is the Airbus Back? Whatever else, Airbus cannot be accused of failing to put on a brave face at this week"s Paris Air Show, held every two years. Louis Gallois is the troubled European air-frame-maker"s third chief executive within 12 months. But still he declared: "I can tell you with full confidence that Airbus is back and fully back." Supporting his confident public message was an extraordinary flow of orders and commitments for over 600 aircraft accumulated in time for the show by the firm"s super-salesman, John Leahy. Although it is heading for a second successive loss—last year it plunged 572m ($ 718m) into the red—Airbus is undoubtedly in better shape than it was 12 months ago when wiring problems delayed the A380 and the weak dollar exposed the firm"s bloated cost base. It has begun the "Power8" recovery plan, intended to save 2 billion annually by cutting 10,000 jobs and auctioning off six factories to partners. And the giant A380 will begin commercial service with Singapore Airlines in the autumn, although being two years late. In the contest between the twin-engined wide-body Boeing 787 and the A350 XWB, Mr Gallois struggles to be as positive. The 787 is already a sales phenomenon, with over 630 firm orders even before the plane"s roll-out next month. The airlines are excited by its revolutionary use of a composite material called carbon-reinforced plastic (CRP). Five years behind the 787, which will enter service next year, the A350 contains a similar share of composite material, but is based on a less advanced structural design that involves hanging CRP panels on a titanium frame. Boeing acknowledges that the A350 may be as light as the 787, but argues that it will be a less pleasant plane to fly in and a more difficult one to maintain. Mr Gallois admits that following Boeing"s approach would have been too expensive and risky for Airbus. At the same time Mr Gallois bemoaned the advantage his rival has in government-supported research and development. Boeing, he claims, receives about $800m a year—ten times as much as Airbus. Earlier in the week, during meetings with ministers representing the four Airbus partners (France, Germany, Britain and Spain), he asked them to fund half the company"s planned 600m-a-year investment in research and technology. He is not hopeful. But for the moment what matters most for Airbus is that the market stays strong and that it gets to grips with its costs. This may require going further in imitating Boeing"s risk-sharing partner (RSP) model than Airbus seems willing to contemplate. According to some estimates, about 80% of the work on the 787 is outsourced to RSPs, saving Boeing both precious development time and working capital. What this week has shown is that for all the success of the 787 and the mistakes of Airbus, the competitive duopoly of the past decade is still firmly in place. But will things stay that way? That depends partly on whether Airbus really has learnt its lessons and partly on who else wants to get into the game. Boeing reckons that in 20 years, 36% of the market will be in the Asia-Pacific region. For the time being, the Chinese, the Indians and others are happy to be partners and customers. But that could change.

单选题Customers often {{U}}defer{{/U}} payment for as long as possible.

单选题His shoes were shined to perfection.

单选题The Olympic Games attempt to transcend national interests and bring together the best international athletes in a spirit of friendly competition and peace.A. debateB. celebrationC. instructionD. rivalry

单选题Sharpshooter Annie Oakley performed {{U}}astonishing{{/U}} feats of marksmanship as the star of Buffalo Bill's Wild West Show beginning in 1885.

单选题I rarely play basketball.A. normallyB. seldomC. frequentlyD. usually

单选题Columbus discovered America while seeking a trade route to Indi

单选题Exercise Whether or not exercise adds 16 the length of life, it is common experience that a certain 17 of regular exercise improves the health and contributes a feeling of well-being. Furthermore, exercise 18 involves play and recreation, and relieves nervous tension and mental fatigue in so doing, is not only pleasant but beneficial. How much and what kind of exercise one should 19 merits careful consideration. The growing child and the normal young man and young woman thrill with the exhilaration of strenuous sports. They fatigue to the 20 of exhaustion but recover promptly with a period of rest. But not so with 21 of middle age and beyond. For them moderation is 22 vital importance. Just how much exercise a person of a given age can safely take is a question 23 to answer. Individual variability is 24 great to permit of generalization. A game of tennis may be perfectly safe for one person of forty but folly for another. The safe limit for exercise 25 on the condition of the heart, the condition of the muscles, the type of exercise, and the regularity with which it is taken. Two general suggestions, however, will 26 as sound advice for anyone. The first is that the condition of the heart and general health should be 27 periodically by careful, thorough physical examinations. The 28 is that exercise should be kept below the point of physical exhaustion. What type of exercise one should 29 depends upon one"s physical condition. Young people can safely enjoy vigorous competitive sports, but most older persons do better to limit themselves to less strenuous activities. Walking, swimming, skating are among the sports that one can enjoy and safely participate 30 throughout life. Regularity is important if one is to get the most enjoyment and benefit out of exercise.